The healthy vagina is maintained by the interaction of the vaginal epithelium and the microbial flora, where lactobacilli play a crucial role. Lactobacillus species maintain the pH acidity in the vagina by the glucose metabolism; moreover, together with the hydrogen peroxide and bacteriocin-like production they suppress the growth of pathogens and other unwanted microorganisms. This contributes to a successful protection against uropathogens causing urinary tract infection (UTI), the disorder bacterial vaginosis and yeast vaginitis by Candida albicans (Reid G, Bruce A W. Urogenital infections in women: can probiotics help? Postgrad Med J 2003; 79: 428-432.).
The Lactobacillus species dominating in the vagina has for long been accepted to be Lactobacillus acidophilus, but the use of genotypic identification methods have demonstrated that the most common lactobacilli species in the healthy vagina are actually Lactobacillus crispatus, Lactobacillus gasseri, Lactobacillus iners and Lactobacillus jensenii. However, separate studies demonstrate differences between the lactobacilli recovered from the vagina showing species such as Lactobacillus rhamnosus, Lactobacillus pentosus, Lactobacillus fermentum, Lactobacillus plantarum and Lactobacillus acidophilus as the dominating lactobacilli, this is probably due to differences in the handling of samples, vaginal status or the methods preferred for the isolation (Vasquez A, Jakobsson T, Ahrné S, Forsum U, Molin G. Vaginal Lactobacillus flora of healthy Swedish women. J. Clin. Mirobiol. 2002; 40: 2746-9).
The World Health Organization defined probiotics as “live microorganisms which when administered in adequate amounts confer a health benefit on the host”. The development of antibiotic resistance and failures in vaginal infections treatment have risen an increased interest in probiotics as an alternative tool. The need for a vaginal probiotic is clear in terms of the high number of incidence of vaginal infections recurrence (Reid G, Bruce A W, Fraser N, Heinemann C, Owen J, Henning B. Oral probiotics can resolve urogenital infections. FEMS Immunol Med Microbiol 2001; 30: 49-52; Famularo G, Pieluigi M, Coccia R, Mastroiacovo P, De Simone C. Microecology, bacterial vaginosis and probiotics: perspectives for bacteriotherapy. Med Hypotheses 2001; 56: 421-30.). A change in the vaginal flora characterized by the decrease of lactobacilli appears to be the major factor causing the syndrome bacterial vaginosis. Regular administration of a Lactobacillus strain with ability to colonize vagina can be an alternative solution for this problem.
Yoghurt treatment as a household remedy has been used for years for prevention or relief of vaginal disorders. However, Lactobacillus delbreukii var. bulgaricus, the lactobacilli found in yogurt is not an optimal candidate for vaginal restoration by probiotics because it's not normally found in that environment and does not adhere well to the vaginal epithelial cells for successful colonization (Famularo G, Pieluigi M, Coccia R, Mastroiacovo P, De Simone C. Microecology, bacterial vaginosis and probiotics: perspectives for bacteriotherapy. Med Hypotheses 2001; 56: 421-430). The optimal candidates for such a vaginal probiotic are species that are normally found in the vagina and possess qualities to suppress pathogens.
The normal vaginal flora ascends from the rectal mucosa (Reid G, Bruce A W. Urogenital infections in women: can probiotics help? Postgrad Med J 2003; 79: 428-432), which means that orally administrated microorganisms that survive the gastrointestinal passage will appear in the vagina after a certain time. This fact raises the possibility of a vaginal probiotic that can be given orally to the host which simplify long term administration with the intention to prevent vaginal problems.
Women given L. acidophilus during 6 moths resulting in a decrease in both candidal colonization and infection (Hilton E, Isenberg H D, Alperstein P, France K, Borenstein M T. Ingestion of yogurt containing Lactobacillus acidophilus as prophylaxis for candidal vaginitis. Ann Internal Med 1992; 116: 353-357).